Gas turbine engines having can combustors employ a transition duct to direct combustion gases from the combustor to a first row of vanes. In some configurations relative growth resulting from thermal transients during operation as well as relative movement that occurs during normal operation have been accounted for by installing rigid floating seal between the transition duct and the row one vanes. The transition-to-vane floating seal is configured to span a distance between a downstream end of the transition duct and the row one vanes, to permit relative radial and axial motion between a downstream end of the transition duct and the row one vanes, and to contain the gases.
In one configuration the same structure that enables the relative motions also creates a leakage path between the downstream end of the transition-to-vane floating seal and between the row one vane and the transition-to-vane floating seal. The transition duct, the floating seal, and the row one vanes are disposed in a plenum and are surrounded by cooling fluid that is normally at a slightly higher static pressure during operation. These leakage paths permit cooling fluid present in the plenum surrounding to leak into the combustion gases. The leaked air bypasses the combustor and hence does not contribute to the engine output, and this reduces the engine's efficiency. During transient pulsations the static pressure of the hot gases may temporarily spike to a static pressure above that in the plenum. This may cause a reversal of a flow direction in the leakage paths, thereby permitting hot combustion gases to enter and damage the leakage paths. Consequently, there remains room in the art for improvement.